The influence of bicine on the hydration and properties of Portland cement

Nitrogenous strength enhancer is an organic chemical additive, which is popularly used to regulate cement hydration and improve cement properties. In this work, the effect of N, N-di(hydroxyethyl)glycine (bicine) on the hydration process and the properties of Portland cement were systematically investigated. The results obtained indicate that bicine significantly changes the morphology of portlandite crystals from a parallel-stacked lamellar shape to a distorted one and also decreases the pore size of the hardened cement paste at early age. The C–S–H phase in the hardened cement paste presents a higher Ca/Si ratio when adding bicine. Additionally, low doses of bicine can accelerate the hydration of C 3 A and C 3 S at lower dosage and promote the conversion of AFt to AFm. Thus, the mechanical performance would increase 30.9% and 13.6% at 3 d and 7 d only with 0.03% bicine, respectively. However, adding excessive bicine is not beneficial for the strength development in the early and late ages.